*, *:before, *:after {
    box-sizing: border-box;
}

html {
    font-size: 18px;
    line-height: 1.5;
    font-weight: 300;
    color: #333;
    font-family: "Nunito Sans", sans-serif;
}

body {
    margin: 0;
    padding: 0;
    height: 100vh;
    background-color: #ecf0f9;
    background-attachment: fixed;
}

.content {
    display: flex;
    margin: 0 auto;
    justify-content: center;
    align-items: center;
    flex-wrap: wrap;
    max-width: 1000px;
}

.heading {
    width: 100%;
    margin-left: 1rem;
    font-weight: 900;
    font-size: 1.618rem;
    text-transform: uppercase;
    letter-spacing: .1ch;
    line-height: 1;
    padding-bottom: .5em;
    margin-bottom: 1rem;
    position: relative;
}
.heading:after {
    display: block;
    content: '';
    position: absolute;
    width: 60px;
    height: 4px;
    background: linear-gradient(135deg, #1a9be6, #1a57e6);
    bottom: 0;
}

.description {
    width: 100%;
    margin-top: 0;
    margin-left: 1rem;
    margin-bottom: 3rem;
}

.card {
    color: inherit;
    cursor: pointer;
    width: calc(33% - 2rem);
    min-width: calc(33% - 2rem);
    height: 400px;
    min-height: 400px;
    perspective: 1000px;
    margin: 1rem;
    position: relative;
}
@media screen and (max-width: 800px) {
    .card {
        width: calc(50% - 2rem);
    }
}
@media screen and (max-width: 500px) {
    .card {
        width: 100%;
    }
}

.front,
.back {
    display: flex;
    border-radius: 6px;
    background-position: center;
    background-size: cover;
    text-align: center;
    justify-content: center;
    align-items: center;
    position: absolute;
    height: 100%;
    width: 100%;
    -webkit-backface-visibility: hidden;
    backface-visibility: hidden;
    transform-style: preserve-3d;
    transition: ease-in-out 600ms;
}

.front {
    background-size: cover;
    padding: 2rem;
    font-size: 1.618rem;
    font-weight: 600;
    color: #fff;
    overflow: hidden;
    font-family: Poppins, sans-serif;
}
.front:before {
    position: absolute;
    display: block;
    content: '';
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(135deg, #1a9be6, #1a57e6);
    opacity: .25;
    z-index: -1;
}
.card:hover .front {
    transform: rotateY(180deg);
}
.card:nth-child(even):hover .front {
    transform: rotateY(-180deg);
}

.back {
    background: #fff;
    transform: rotateY(-180deg);
    padding: 0 2em;
}
.card:hover .back {
    transform: rotateY(0deg);
}
.card:nth-child(even) .back {
    transform: rotateY(180deg);
}
.card:nth-child(even):hover .back {
    transform: rotateY(0deg);
}

.button {
    transform: translateZ(40px);
    cursor: pointer;
    -webkit-backface-visibility: hidden;
    backface-visibility: hidden;
    font-weight: bold;
    color: #fff;
    padding: .5em 1em;
    border-radius: 100px;
    font: inherit;
    background: linear-gradient(135deg, #1a9be6, #1a57e6);
    border: none;
    position: relative;
    transform-style: preserve-3d;
    transition: 300ms ease;
}
.button:before {
    transition: 300ms ease;
    position: absolute;
    display: block;
    content: '';
    transform: translateZ(-40px);
    -webkit-backface-visibility: hidden;
    backface-visibility: hidden;
    height: calc(100% - 20px);
    width: calc(100% - 20px);
    border-radius: 100px;
    left: 10px;
    top: 16px;
    box-shadow: 0 0 10px 10px rgba(26, 87, 230, 0.25);
    background-color: rgba(26, 87, 230, 0.25);
}
.button:hover {
    transform: translateZ(55px);
}
.button:hover:before {
    transform: translateZ(-55px);
}
.button:active {
    transform: translateZ(20px);
}
.button:active:before {
    transform: translateZ(-20px);
    top: 12px;
}
